Shellfish, such as mollusks and, more specifically, oysters, act as both a food source and a natural protectant to coastlines. Mollusks are in the scientific class Biealvia and include species such as clams, oysters, scallops, muscles, etc. Mollusks tend to live in clusters with reproduction typically occurring through the release of sperm or eggs into the water. The steps of fertilization, hatching, and larval development occur in plankton community (free floating). Larvae continue to float in the water until, after a given period of time, they are ready to attach to a suitable substrate. The process of attaching or catching to a surface is called “cultching.” The catching or substrate material is referred to as “cultch” and recently settled oysters are known as “spat.”
The freshly settled or cultched oysters are prone to predators, such as crabs, starfish, oyster drills, and other predators. Mollusks, such as muscles and oysters, also must compete with barnacles, slipper shells, sponges, and other sea life for space and food. For instance, shrimp are known to burrow into oyster beds, which can smother young oysters and/or damage the desirable oyster-growing conditions. Oyster drills are small snails that move across oyster beds in order to find and eat oysters. Oyster drills have the ability to soften the shell of shellfish and other marine animals, but they prefer juvenile oysters. For that reason, oyster growers sometimes attempt to cultivate oysters in lower salinity waters that is tolerable to oysters but not to snails.
To develop as a food crop, oyster spat will ideally attach to a fixed substrate that provides predatory protection, nutrients for growth, and ease of later harvesting. Typically, old shells from previously harvested oysters are used as cultch. One known technology for oyster cultivation is, therefore, to dredge old oyster shells, clean the shells via high-pressure water hoses or other means, and to place the shells in desired locations for oyster development. Oyster growers have also devised “setting” tanks. These tanks contain seawater that is aerated and heated. The tanks are filled with bags of clean shell to catch the shellfish seed. Larval shellfish and oysters are added to the cultch-filled tanks. The problems with known techniques include the fact that the dredging of old mollusk beds for mollusk shells may negatively impact the environment. Special tanks or cultch structures have often proven to be expensive or ineffective.
Shellfish beds also provide environmental enhancements such as the reduction of erosion and reduced wave and storm damage to a coastline. Large shellfish reefs such as oyster reefs, are known to reduce the size and intensity of waves and to reduce erosion. These natural beds are advantageous relative to artificial reefs because artificial reefs currently require the use of large, heavy equipment to drop large limestone rocks or other material as breakwaters. The equipment, along with the types and size of the artificial material, can damage the area that the breakwater is intended to protect by the placements of the artificial reefs.
Current materials used for artificial reefs can include scrap material that is not suitable or desirable for organism growth. While such artificial reefs may mitigate coastal damage or erosion, a healthy ecosystem requires a reef material that promotes or encourages organism growth. Therefore, it has also been desired that a material for artificial water-based structures encourage the growth of other organisms such as beneficial bacteria, plants, and other animal species.
Bacteria that is important to the nitrogen cycle (a biogeochemical cycle that describes the transformation of gaseous nitrogen into forms useable by living organisms and vice-versa), such as nitrosomonas or nitrobacter, and other bacteria often improve water quality or otherwise contribute to an ecosystems health and stability. Obviously, plants such as spartina alterniflora cordgrass, freshwater plants, algae, red mangroves, or other water-based plant species are desirable in many healthy ecosystems. Corals, barnacles, and nonsessile but stabilizing organisms form a part of healthy ecosystems as well. ‘Stabilizing’, in this context, means communities of organisms that expand over time to provide structural protection to a shoreline. ‘Stabilizing’ also applies to organisms that provide other positive effects to an aquatic ecosystem, such as acting as a filter, releasing nutrients, and the like. Scientists have sought the development of an artificial material that is suitable as a building material that would also increase, encourage, or otherwise facilitate the growth of these desirable organisms.
Therefore, there exists a need to create an artificial material for the production of structures that would facilitate the setting and growing of numerous organisms. The material would ideally encourage the growth of many other desirable or necessary organisms such as mollusks, bacteria, algae, plants, and non-mollusk animals. A composite material providing nutrients and the required structural integrity has been sought. Optionally, the artificial material would include means to reduce the impact of predators on cultched mollusks such as oysters. The present invention solves one or more of these other needs.